This is the 10th and 11th in a series of meetings devoted to opportunistic protists that cause serious problems in AIDS patients and other individuals with defective immune systems. The 1st meeting was initiated to serve the small, but growing international scientific community interested in working with the unusual, non-cultivatable organism Pneumocystis. At the time, Pneumocystis was relatively unknown and was ignored by many in the microbiological community. There was a need for a small meeting where scientists could exchange new techniques and experiences gained from working with these 'difficult'organisms. A basic tenet of these Workshops is a free exchange of information facilitated by open admission to the meeting. The 2nd through 9th Workshops grew to include other opportunistic organism-based community groups that experience many of the research challenges facing the Pneumocystis community. The International Workshops on Opportunistic Protists (IWOP) now include research presentations on Cryptosporidium;the microsporidia;Toxoplasma gondii;and free- living amebae turned pathogenic. In recent years, IWOP has begun serving as a forum for researchers of kinetoplastid flagellates and other eukaryotic microbial parasites that are caused by different genotypes or present pathologies in immunodeficient individuals distinct from that observed in immunocompetent patients . Today, IWOP is regarded as the most important meeting for most researchers of Pneumocystis, Cryptosporidium, and the microsporidia. IWOP- 10 is scheduled for May 28-31, 2008 in Boston, Massachusetts just before the start of the American Society for Microbiology General Meetings. IWOP-11 is tentatively scheduled for the summer of 2010 in Hilo, Hawaii. NIH grant management: University of Cincinnati Cincinnati, Ohio 45221 Workshop Sites: IWOP-10, 2008, Boston, Massachusetts IWOP-11, 2010, Hilo, Hawaii Edna S. Kaneshiro Univ. Cincinnati P.I. Melanie T. Cushion Univ. Cincinnati Co-Investigator Elizabeth Didier Tulane Natl. Primate Res. Ctr Co-Investigator Francine Marciano-Cabral Medical College of Virginia Co-Investigator Olga Matos Inst. Higiene Med Tropical, Lisbon Co-Investigator Sheila Mitchell Virginia Tech Co-Investigator Nhu-An Nguyen Univ. Cincinnati Co-Investigator Anthony Sinai Univ. Kentucky Co-Investigator Louis Weiss Albert Einstein College of Medicine Co-Investigator Lihua Xiao CDCP, Atlanta Co-Investigator This is a proposal for funding for partial reimbursement for approximately 50 students, post- doctoral researchers, young investigators, and junior faculty to attend the 10th and 11th International Workshops on Opportunistic Protists. The Workshops focus on advances on understanding eukaryotic microbes that infect and can cause life-threatening infections in AIDS patients.